1. Field of the Invention
The present invention pertains broadly to a ductless system for conditioning the air within the interior of an enclosed building, and more particularly to such a system utilizing a global control concept wherein the interior of the building is maintained at a pressure greater than the outside atmosphere, and air is emitted at various points around the perimeter of the building in controlled amounts in response to observed atmospheric conditions at corresponding locations within the building, so that conditioned air migrates to the locations as needed to maintain the atmospheric conditions within prescribed parameters.
2. Description of the Prior Art
Industrial-type buildings heretofore have generally been heated from a central heating plant, with ducts or pipes delivering heated air, steam or hot water as a heat carrying medium to various areas of the building for distribution of the heat. Cooling is likewise provided by delivering conditioned air from a central unit or units through ductwork to specific discharge areas. Ventilation is provided by extracting stale or polluted air, often with the assistance of a large number of fans, through vents in the roof or walls.
There has heretofore been little or no correlation between the heating or cooling and the ventilation. Due to the manner in which the heating and/or cooling is effected, substantial temperature differentials are created in different areas of the building as well as at different elevations within the building. The ductwork and piping necessary to distribute the heating or cooling medium is costly to install and maintain and, due to frictional losses within the ductwork and piping systems, significant amounts of energy are expended in operating them.
In recent years direct-fired space heating units have been developed for heating relatively large industrial type buildings as disclosed, for example, in U.S. Pat. Nos. 3,398,940 to Kosarin and No. 3,542,373, 4,325,352 and 4,429,679 to Dirkes. Such units are generally located exteriorly of the building, as on the roof thereof, and include a sheet metal cabinet housing a burner and a fan. The fan draws fresh air from the outside, as well as return air from the interior of the building. A portion of the fresh air is drawn over the burner to be heated, and the remaining fresh air is mixed with recirculated building air in selected proportions. The heated and unheated air are combined downstream from the burner and discharged into the building to maintain the building interior at a desired temperature and pressure. Such units allegedly maintain temperature and pressure at desired levels by altering, on demand, the complementary proportions of outside air and recirculated building air passing through the unit or units for discharge into the building. No ductwork is employed, and once the air is discharged into the building its movement is randomly affected by various factors such as building infiltration, exfiltration, convection currents, heat producing activities in various areas of the building, air density differentials and ventilation systems. Thus, while the space heating units themselves may perform very well, their operation often results in objectionable and uncontrollable hot or cold areas within the building. Furthermore, they are not effective in removing airborn pollutants and contaminants from, or controlling humidity in, localized areas of the building.
Various ventilating systems have been proposed, particularly for poultry and livestock buildings, which employ adjustable dampers in air inlets or outlets for regulating air inflow or outflow. Such devices typically include a wall or roof vent having an adjustable shutter or louver which is operable by a servomotor. The servomotor may be centrally controlled to appropriately set the shutter in response to signals indicative of, for example, temperature or humidity so that varying amounts of air can be admitted or exhausted through the shutter at a more-or-less uniform velocity.